Virtual Reality (VR) may be referred to as immersive multimedia or computer-simulated reality. VR, AR, MR and other types of reality are sometimes referred to as X Reality (XR) to cover multiple types of reality. It is frequently associated with a variety of applications, which may comprise immersive, highly visual, computer-simulated environments. These environments typically simulate a physical presence of a user in places in the real world or imagined worlds. Related thereto is Augmented Reality, wherein the computer simulations comprise a direct or indirect view from actual physical world, with objects augmented or supplemented by graphical images. The computer simulation of these environments is commonly achieved by visual images and auditory signals.
Visual images are commonly presented by means of a video display that forms part of a head mounted display (HMD) and may encompass all or part of a user's field of view. The HMD may be arranged as a visor, helmet or other suitable configuration. An example of a HMD presently available is the Oculus Rift from Oculus VR. A further example of a HMD presently available is the HoloLens from Microsoft.
The HMD is usually arranged to cover the eyes of a user such that a user wearing the HMD can see only the virtual world and is thus unable to see the actual physical world. In the physical world a user is normally able to see his or her arms, legs and torso when they are within their field of view. A known system for determining a position and orientation of a body parts of a user is by attaching to the HMD a camera, which is able to provide images for tracking body parts. A further known system comprises a magnetic field based tracking system, which requires attaching to the user trackers arranged within a magnetic field. Such an arrangement is disclosed in U.S. Patent Application No. 2011/0032187. U.S. Pat. No. 8,140,970 shows a method for displaying a virtual keyboard with a semi-transparent overlay of an end user's hands, where the user's hands are captured by a video camera.
One issue with transitioning between AR and VR states is determining when to transition. One approach is detecting when the user is interacting with an object to be used for AR, or otherwise based on a user's location, such as described in the following: U.S. Pub. No. 20160314624 (interaction with an object or user's location in a scene triggers transition); U.S. Pub. Pub. No. 20150123966 (describes an incremental transition).
In spite of the considerable effort already invested in the development of said systems further improvements are desirable.